Electrochemical corrosion of silicon carbide ceramics in H2SO4

Electrochemical corrosion of silicon-infiltrated silicon carbide ceramics in aqueous solutions

“…In contrast, formation of a SiO 2 layer was observed in acids. The results indicated surface passivation by formation of the SiO 2 layer according to the high-field mechanism [8].…”

“…The local corrosion rate of the grains was found to be controlled by the local resistivity, depending mainly on the resistivity of the grain boundaries [8,15]. No correlation between the corrosion rate and the polytype or the crystallographic orientation was found in acids or alkaline solutions [8,15]. In LPS-SiC materials, with grains exhibiting a core-rim structure, the rim exhibited a higher corrosion rate.…”

“…SiC ceramics exhibit high chemical stability, but can undergo elecrochemical corrosion, depending on the preparation, phase content and electrical conductivity [8][9][10][11][12][13]. However, the corrosion rates of ceramics are generally very low compared with those of metals.…”

“…However, the corrosion rates of ceramics are generally very low compared with those of metals. Over the last few years the electrochemical corrosion behaviour of solid phase-sintered SiC ceramics and liquid phasesintered SiC ceramics (LPS-SiC) has been investigated [8][9][10][11][12][13][14]. The investigations of the SSiC materials showed an inverse relationship between the corrosion rate and the resistivity of the material.…”

“…The authors assumed that silicon was the reason for the stronger corrosion, but they did not proof this assumption by carrying out the associated microstructural investigations. For SiSiC ceramics, not only the described electrochemical dissolution of SiC [8,12,13,15], but also the electrochemical corrosion of Si in acid and alkaline solutions, has to be considered. The following half-reactions are involved:…”